The ICD10 was revolutionary. It incorporated the outcomes of numerous collaborative studies and programmes, both national and international and included input from the American Psychiatric Association, the publisher of the Diagnostic and Statistical Manual (DSM), the ICD's equivalent in North America). Consequently, the ICD and the DSM are now broadly similar.
But, as opposed to the DSM, the ICD provides two sets of diagnostic criteria for each disorder. One list is useful to the diagnostician and allows for some latitude and for the practitioner's exercise of judgment. The other set is far more precise and strict and intended to be used by scholars and researchers in their studies. Yet a third, simplified classification is applicable to primary care settings and contains only broad categories (dementia, eating disorder, psychotic disorder, and so on).
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 2 DVDs with 12 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)